The work involved switched mode power supply design, and the development of measures for Standards compliance. Modifications to the existing design solved a problem with surge sensitivity. Australian conditions make more stringent demands than IEC Standards. The work on the new model required difficult interaction with the consumer products marketing people.

Aerosonde Pty. Ltd http://www.aerosonde.com/
Manufacturers of pilotless aircraft.
August and September 2012
(Short – term contract)

Aerosonde promote themselves this way: “Aerosonde is a strategic business of AAI Corporation, an operating unit of Textron Systems, a Textron Inc. company. We bring small unmanned aircraft system capabilities to the military and scientific communities, both in the U.S. and internationally. Aerosonde’s headquarters, which also serves as the Aerosonde aircraft manufacturing facility, is located in Victoria, Australia. Final Aerosonde aircraft integration is accomplished at AAI in its Hunt Valley, Md location. Flight operations are conducted in Victoria, Australia, and at Wallops Flight Facility in the United States and at various customer sites.”

Aerosonde started out (as their name implies) building vehicles for carrying a payload of atmospheric research instrumentation. The sale to the American principal represented a move to capture a wider and international market, which appears to be mainly military.

I was employed in the electronics production area. The work included electronic assembly work, testing, development of testing methods, design of test jigs. The work was only short term as it related to the completion of a particular contract.

Lessons learned.
It was interesting to observe the production control procedures in place in a company oriented to the military market place. I worked close to people building engines and other features not normally found in electronic manufacture. I learned a lot from them. Aerosonde expands its workforce during large contracts. This presents difficulties where a high proportion of the staff are new. I was exposed to the tackling of interesting management issues.

Hydrix (http://www.hydrix.com/)
April 2010 – July 2012

Full time employment under the title “Senior Engineer”

Principal Engineer in several projects developing swimming pool chlorinators, and smaller contribution to other projects.
Detailed design of switch mode power supplies
Supervision of others (engineers, technicians, pcb layout CAD operator)
Mentorship of younger engineers
Project documentation (Requirements, Design Notes, Design Test Plan, Test Reports, manufacturing Test procedure)
Writing ISO 9001 procedures
First Aid Officer

Australian Model Engineering Magazine
2009 (continuing)

In my own column named “Sparks 'n' Arcs” I am writing a series of articles for Australian Model Engineering Magazine to explain electronics to a readership with a strong mechanical background. A sample of these are to be found at http://home.exetel.com.au/rwombat/Sparks_n_Arcs/

Lessons learned.
In a way, writing a tutorial column is like running a class, except you get much less feedback, and that from a particular, small sample (if readers send emails). I have set out to provide something for everyone over a wide range of background understanding. Feedback indicates that there has been success.

Omnitron Technologies http://www.omnitron.com.au/
February 2009 – November 2009
Electronic Design Engineer (contractor)

Design and development for manufacturing of a heavy current transmitter for geophysical research. I have made some advancements to the art in which very fast on and off transitions are required in current waveforms of 50 amps magnitude.
Designed the control and alarm/safety circuits.
Neither Omnitron nor I had a chance to utilize established project management processes, as the requirements of the client determined these details.

Lessons learned.
Sometimes it really is worthwhile to go right back to fundamentals and solve some equations and get a really clear picture of what is going on. When is this worthwhile, and when is it a diversion? This must be a judgement based on experience, and there is no simple formula for it.

Air-Met Scientific Pty. Ltd. http://www.airmet.com.au/
December 2004 – September 2006
(Manufacturer and import agent for toxic gas sensing instruments)

Technical Services Manager

Airmet was a small company situated in Blackburn which was a gas contaminant monitoring equipment merchant, and a developer of air contaminant monitoring equipment.

I wrote quality manual procedures for design and design project management.
(ISO9001/and for the laboratory IEC17025)

I developed an engineering documentation and release system based on html files and hyperlinks between files. This provides all information required by the purchasing officer to initiate orders on contractors to bring about a production run, and all technical information required by in-house staff performing final assembly and calibration/config and service. The work instructions and other documents in this system form part of Air-Met's ISO9000 Management System. I was responsible for the management of all production issues and engineering aspects of outsourcing of pcb assemblies. However this system was set up so that repeat ordering will take place without engineer input.
I was responsible for the mentorship and supervision of younger Engineers
For a time, I was Manager of Service Department. I held this role for eight months, and relinquished it in a rearrangement of roles that enabled me to focus on R&D work.
I was responsible for technical and engineering support to the service team. I conducted training and acted as consultant to assist with odd-ball or particularly difficult service tasks.
I was manager of all Technical aspects (except gas chemistry matters) of the "Fixed Systems" part of the Air Met business. Whereas portable instruments are usually fully imported and require no local engineering, the fixed systems work involved locally (in-house) designed and manufactured product and job-by-job system design and project management. With this role, I designed and brought into manufacture the "Monotox 5000" toxic gas sensing instrument.

Lessons learned.
I had taught myself about html in my own time, but this was my chance to apply it in the manufacturing management system. The electronics work in this job did not present any new lessons for me. I learned to discharge my responsibilities in a company that was primarily a merchant with very little allowance for development work in the company culture.

Nilsen Industrial Electronics (This company no longer exists. No web site)
Heidelberg West
(Manufactured electronic domestic kilowatt-hour meters)

1993 – 2004

When I joined Nilsen again, (see below) the electronic kilowatt hour meter that I had been project leader for the development of in 1982 and 1983, had been in production for some years. The new task was to develop an enhanced model. One aim was to change from Class 2 (plus or minus 2% accuracy) to Class 1 (plus or minus 1% accuracy).
This matter of product accuracy is widely misunderstood. Many component manufacturers offer components that they claim will “meet Class 1”, but on examination one finds that the component is taking up the whole of the error budget for the Class 1 product. One percent is the total error of the final product at the factory door, and includes errors due to the calibration test set, and every source of error within the product.
I discovered that some of the early concept work of the existing product had not been understood by my successors, and opportunities to optimize performance had been missed.
The new meter was designed around a Motorola 68HC11 microprocessor.
Enhancements introduced by me included:

Matching the phase response of the voltage and current inputs.
Software based phase error correction
This scheme, which was all my own work, was implemented in the meter. Some years later, salesmen from TI attempted to tell me under protection of a non-disclosure agreement about pretty much the same scheme! The idea is that if you pick two points on a sinusoidal waveform that are close together in time compared with a half period, and then do a straight line interpolation between them, then as the pair of points move along the sinusoid, the interpolation point will also be a sinusoid. As the spacing between the points is increased, the amplitude of the interpolated sinusoid will decrease. Thus the interpolation acts as a low pass filter. The use of this in the meter is that there is a standing error between the phase of the voltage path and the phase of the current path. This can be nulled if the following sequence is followed: Current measurement, fixed delay, voltage measurement, fixed delay, and then a second current measurement. Linear interpolation can then be performed on the two current measurements and by varying the weighting of each, the effective resultant phase of the composite current measurement can be varied over a small range. It is an easy matter in the test set to adjust this so that the phase of the composite current sinusoid matches that for the voltage with errors in the input circuits cancelled.

Introduction of pseudo random sequence generated dither signal
Interference cancelling and copper-drop nulled shunt circuit geometry.
Wide dynamic range optical port.

Other projects that I was responsible for included:

"Smart Probe" optical reading head with built-in protocol conversion. This device is for electricity meter reading in combination with a palm-top computer. Hardware design (including die-cast case) and software - 6805 assembler code.
Development of a system and associated hardware called "Meternet" which allows meters to be networked for remote reading (large residential complexes) (Software by others)
Development of a provision for registering a count of pulses from sources such as water or gas meters (to incorporate "dumb" devices in remote reading systems) Utilized PIC 12CXXX processors. Used special data format (edge-time-encoded) to provide immunity to telegraph distortion and reduce cost. Software necessarily written in assembler as it manages sub-microsecond timing of the communications protocol.
Concept development for new meter model (NEC `UPD780308 based) a cost reduction exercise. (This was later in production for three years at about 40 000 units per year.)
Continuing cost reduction minor design modifications. About $10.00 per unit or $400,000 pa resulting from my innovations.

I was not a team leader in this role, but I was responsible for mentorship of younger engineers. Developed working protocols for maximum synergy for groups with diverse skills.

Variant management system
The Nilsen meter was manufactured in many variants. It seemed that each customer had his own requirements, and ever keen to bend to the customer's whim, the sales people were always demanding a “special” to get their next order. Administering this had become a nightmare. The Engineering Parts List was a document with many columns: one for each variant. For each component, there was an asterisk in those columns for which the component was to be used. An encoding scheme had been developed for the sales people to use to assist them in specifying a new variant. This consisted in a build encoding scheme in which the build code format consisted of many fields for which the format and the meaning of each allowable contents of each field was specified. The salesman could sit down with his customer and fill in the fields of this build code as the preferred content for each field was revealled. I named this code the “Pat Code” after the instigator.

I developed the architecture and the code for a computer program which ran the process from the Pat Code to the Engineeering parts List and the pcb loading drawing for the particular build. This was done by modularizing the circuit and prescribing algorithms for the inclusion or exclusion of each module according to PatCode content. The system was implemented and provided a huge reduction in cost in the introduction of each new variant.

Nilsen Industrial Electronics had inherited a highly developed development and manufacturing documentation system, which predated ISO 9001. This was adapted to ISO 9001 with minimal change during my tenure. I contributed to this. Interestingly, there was one area that remained untouched by these formalities. This was the design process. A result was the evolution of a splitting of project management into two parts. One role was the documentation of a plan for a development and the generation of commentary for senior management on how the actual development process (in progress) compared with the plan. The role for this was formally defined, and I played no part in it. A second and completely separate task was the actual conduct of the development so that a design resulted that met the documented requirements. I was responsible for this for many projects. Tasks included:
Allocation of tasks to exploit individual's special skills
Arranging team meetings so that each participant understood his part in the plan.
(particularly meetings between the software and hardware teams)
Adjustment to the project methods as required to ensure that each individual's morale and motivation was high.
Organizing and conducting tutorial meetings when one individual had skills or knowledge that was to be shared with a co-worker.
During my ten tear tenure these tasks fell increasingly to me, and I fine tuned my skills in this area.

Lessons learned.
I learned that senior management can constrain a system design by making assumptions about how things will go without even realizing that they are making assumptions. I gained experience with signal processing, and with seeing ideas about fundamentals followed through to manufactured product.

Ausmode Power Systems/Exicom Australia http://www.exicom.com.au/
1988 - 1992

Ringwood Ausmode Power Systems was a small company set up to design and manufacture power equipment for the telecommunications industry. In the telecommunications industry, it is conventional to power equipment from a DC supply that has a battery floating on it. The equipment that takes power from the mains and provides DC to power the excahnge and to charge the battery is traditionally called a “rectifier”. Ausmode was at the forefront of the introduction of switched mode technology to rectifiers which had hitherto been built around mains frequency power transformer and phase controlled SCRs for output control. After creating the bulk of the intellectual property in the rectifier product lines, and trading for a couple of years, Ausmode was sold to Exicom. Exicon thus became my employer. However despite the change of employer, I continued in the same job.

Project Leader - Uninterruptible power supply (600 VA - for use with a pc.) True sine wave inverter and provision for synchronizing to mains on power restoration for seamless switch back.

Project Leader - Supervisory board for 50 amp rectifier. Analogue and digital controller design. Control of heavy current circuits via fibre-optic link.

Project Leader - Light-current parts of 450 amp and 1000 amp Distribution Module
Managed a team of up to four Engineers, technicians, software writers and CAD designer.
Ausmode did not have formal processes for team management, and I developed these to maximize individual productivity and team accountability.
Heavy Current (shunts on bus bars), and electronics design of a system that monitored energy use in the telecommunications fifty volt dc environment. The equipment had provision for monitoring various alarms and for communications for remote control/monitoring.
Managed the software development, and wrote most of the code which was in Motorola 68HC11 assembler.

I left Exicom because they closed the Melbourne design centre (Old Ausmode site), and could only offer me continuing employment in Sydney, which was not of interest.

Lessons learned.
In this role, I had the opportunity to have “hands on” with the software architecture and coding. The result was successful, and I was able to have other software people write code that would fit in seamlessly. I gained much more extensive experience with phase locked loops and with control loops (with a particularly difficult plant) generally. I learned a lot from colleagues who had specialized in switched mode circuitry more than I had. I managed a team of up to four people.

Futuretech Pty. Ltd. Oakleigh
1985 - 1988

Futurtech was a company formed by two ex employees of an HF radio manufacturer. As well as the design offices, there was a small-run manufacturing facility. Futuretech had some products of its own, and performed board loading for others. It was always on the lookout for the “Design and Build” (in small quantities) project. I was employed to manage the development of a frequency division multiplex equipment test system. This gave me the opportunity to delve much more deeply into the design of phase locked loops for demanding applications. This in turn led to the development of an agile multi frequency tone generator for L. M. Ericsson. For some time, I was the Project Leader for a hydrographer's telemetry system for the Dandenong Valley Authority. The constraints of the established project management methods were tight, but within these, I took responsibility for maximizing the productivity of the team by careful allocation of tasks and mentorship of team members. I left because, within that particular management structure, I was not able to contribute in ways that I believed the project required, and I was “head hunted” by Ausmode.

Lessons learned
If a project is to succeed, the senior management, and not just those working on it, have to be “signed up” to it. I learned a lot about phase locked loops and gained further experience with logic and microprocessor applications.

Schurmann Design Pty. Ltd. , Warrandyte
1983 - 1985

This was my own company. I worked from a “home office” with one technician. Several design projects were carried out. These were the early days of applying microprocessors to small products.

I had contact with the people at the Ford Motor company warehouse, and they engaged me to take an investigatory trip to Detroit and Atlanta USA to evaluate radio link data terminal system. On my return, I reported favourably, and then installed and commissioned the system. This involved the manufacture of a special interface between the Ford Burroughs computer system and the radio terminal system.

Lessons learned.
Running my own company. I learned that I could be devoting my brain to electronic development problems, or I could focus on matters pertaining to the running of the company, but not both at once. This really brought home to me the extent to which a design engineer's job takes up part of his mind 24 hours a day. Some useful lessons in dealing with an overseas supplier, installing equipment on a main frame computer, and general product development.

Nielsen Development Laboratory , Fitzroy and Heidelberg
1982 - 1983

Started by Oliver J. Nielsen in 1916, this company grew into a major electrical equipment manufacturer and contractor. John Nielsen, (grandson of the founder) saw that the company provided everything to go in a domestic meter box except the kilowatt hour meter. He thus instigated the plan to develop one. The existing technology was one or two Ferraris disc meters and a time clock or ripple control receiver. The plan was to develop a single electronic meter that would perform all of these functions. I was employed as project leader.

There is some controversy about who thought up what. However at the earliest part of the project, before other team members were brought in, I established some key principles. I saw the 50Hz mains waveform as a carrier. The rate at which energy is used is a varying quantity, and the waveform of this variation can be regarded as a signal that is used to amplitude modulate the 50Hz carrier. The useful bandwidth of this signal is quite a different thing from the bandwidth of the instantaneous voltage or current or power waveforms. Indeed, as the signal (rate of energy, or power) is to be integrated to get an energy, the bandwidth of the power signal can be reduced considerably without lowering the accuracy of the cumulative answer. As the cumulative answer is the result of the summation of very many samples, the samples themselves can have a much higher quantization error that is acceptable in the answer. Quite large random errors are acceptable in the samples, and these will disappear in the summation as long as they are not systematic.

Important ideas were introduced about how to demodulate the signal from the carrier, but these were not all my own.

I took this project to a stage where working prototypes had been demonstrated.

Lessons learned
I was managing a project in an environment where other development projects were in progress. I could not make my team feel “special” as I had for morale management at Hyteco. A microprocessor development with very different characteristics from my previous experience. This was my first experience with development work in a large manufacturing company.

Hyteco Pty. Ltd. , Clayton
1977 - 1982

“Hyteco” was a hybrid name, for the arm of Ateco (Australian Tractor Equipment Company) that ran “Hyster” fork truck dealerships in Melbourne and Sydney. The dealerships thrived for some years and extended their trade into other warehouse equipment. They employed me to be trained in the USA on a product called the “Pathfinder”, which was a wire guidance system for warehouse trucks that work in very narrow aisles. This system used a 6.25 kHz current in the guidewire, and sensor coils to pick up the magnetic field surrounding this. A simple analogue computer determined steering requirements (for reverse as well as forward travel) from the sensor signals. I was the first person to implement this sort of technology in the Southern Hemisphere, and the first person to adapt the system to a vehicle that was not sold in the US. This was followed by the Hyteco Driverless Tractor System, which was my first project as Project Leader.

The system consisted of a guidewire burried in the warehouse concrete floor and a number of vehicles that would follow programmed routes through the system. The project consisted of the equipment on the tractors to guide them and to control their programmed actions. The work consisted of the development of the guidance system, (based on Pathfinder practice) a communication system to work between the master controller and the tractors and the lineside equipment (location identifiers and turnouts), and adapting all this to tractors that were designed for operation by a driver. The communications system used the guidewire as the comms channel. Traffic from the central controller was by frequency shift keying of a sub-carrier added to the guidepath current. Communications to the central controller was by phase shift keying of a carrier which was derived by multiplying the guidepath frequency by 2.5. A special receiver was immune to the guidepath frequency and its harmonics, and provided for correction of phase drifts as a tractor moved around the system. I was responsible for managing a team of up to five employees and several outside contractors.

The system was an engineering success, but not a commercial success. Each tractor, and the master controller were microprocessor controlled. 6800 microprocessors were used.

I conducted training of the electric fork truck mechanics, and when the R&D department was closed, I developed a plan for the continuing support of the electronics products by the mechanics whilst I worked out a six month notice.

Lessons learned.
It was very instructive to learn how an American design office and manufacturing plant orders its business. I learned a lot about mechanical engineering and hydraulics on the fork trucks. Heavy current electronics in the SCR controlled traction circuits. Management of a development project with a team of up to 6 people. At first, the team was managed on the basis that I could do everything that I asked my people to do, but when a software man joined the team, I had to learn the much more difficult process: managing work that I did not understand the intricacies of enough to do myself. Further experience with training.

Prodata Pty. Ltd. , Collingwood
1977

This small company had a dealership for a series of accounting machines made by Casio. The machines were programmed in a language of their own which used a code of special symbols. The Casio people (Japanese) had not taken up the idea of using Latin alphabet characters in their programming language at that time. The demands for sophistication had overtaken the capabilities of the machines, so ProData utilized Digital Equipment Company PDP11 minicomputers and had a Casio accounting machine compiler written.
These were used without a disc drive as the core memory board of the day had plenty of capacity for the program and the data. There was a lot of interesting work for me adapting accounting machine peripherals to the minicomputer.

Lessons learned
The PDP11 was at the forefront of mini computer development at the time. It was very instructive to design peripherals for it.

Electronic Design Laboratories Pty. Ltd.

1975

This small company had a stock range of products, and pursued “design and build” projects. This was the day when Telecom still refused to allow subscribers to attach privately owned equipment to the network. Ordinary modems were owned by Telecom, and had to be rented as did an ordinary telephone. An exception was where there was a “special” need and a subscriber required equipment that Telecom could not supply. Like many other small companies at the time, EDL was very creative in inventing up “special” needs so that their customers could qualify for privately owned equipment attachment, and avoid the crippling rental of Telecom equipment. Burglar alarm equipment that would place a call and play a recording was popular. I worked on the design of this equipment and on equipment for a telemetry system for the gas utility (Gas and Fuel Corporation). This was the day when pcb layout was done with crepe tape on plastic film. I did a lot of this. In this job, I worked on my first project that used a microprocessor.

Lessons learned
PCB layout using tape. This makes peculiar demands, as making a change is so time consuming, one learns to plan ahead. With practice, one can see several moves ahead like a chess player. In my experience, many CAD operators who are skilled with modern software packages, never learn this. Experience with MSI logic, analogue design, and switched mode power supplies. Learned how the switched network telephone interface works.

Nonoys Pty. Ltd. , Dandenong
1974 – 1975

Acoustic product production management and computer programming

Nonoys was a manufacturing company that used a sheet metal factory to make specialist acoustic products. The two main product lines were duct silencers for the airconditioning industry, and acoustically rated doors. It had been intended to set up an acoustics laboratory, and I was employed to run this. There were delays in setting this up, and I was engaged in assistant factory management and computer programming.

This was before the days of the “personal computer”, but Wang made a machine that they called a calculator, but which served the purpose of a personal computer. It was programmed in BASIC.

I developed programs for the costing of manufacture of standard products in different sizes. Nonoys had provided a large number of silencers for a run-out of air conditioning in schools, a federal government initiative. Then we had the Khemlani affair. The government couldn't pay. Along with many others, Nonoys had to cut back. The laboratory was put on hold and I had to leave.

Lessons learned
Management of a production facility. Metal working processes. Programming architecture and writing.

1973 Final year at Swinburne
For my design project, I looked at sound level meter design problems. It was during this work that I invented the single multiplier RMS detector. This is based on the identity:
A² – B² = (A+B)(A-B)
The signal, A, had a parameter B added to it and subtracted from it using Op-Amps. The sum and the difference were multiplied using a scheme that set the width of a train of pulses by (offset plus) (A-B) and the amplitude by (A-B). When low pass filtered, this pulse train yielded a variable voltage scaled to the product. The low pass filter also served as a loop filter. The output of this was scaled up by a large factor to produce B. If the scale up factor was sufficiently large, then the averaged value of the product was effectively zero, and B represented the RMS value of A. This might not be a commercially important invention today, but it represented a worthwhile advance with what could be done with 1973 technology. It was not commercially exploited.

Lessons learned
I took the year off for full time study primarily to get the qualification, however I was really pleased to find that I had learned a lot. Particularly on the maths subjects Complex Variable and Dimensional Analysis, and in the Control Systems subject.

1973-1974 Tafe teacher RMIT
This was a part time job teaching electronics to tradespeople. It was my only employment whilst a full time student, and I continued with this work into the following year. There was nothing like Level 4 in Training and Assessment then, and the skills of presentation to a group had to be learned on the job. My classes were a diverse lot, and an explanation that suited the brightest would not be grasped by some of the others. If I made it too simple, the smart ones would be bored. Skills learned here are still used today, particularly with my magazine column.

Lessons learned
“Management of a class”, making a presentation of interest for a group with diverse backgrounds with particular emphasis on the range of backgrounds that tradespeople have.

Carr and Wilkinson - Acoustic Consultants
1968 - 1973

At the beginning of 1968, this acoustic consultancy practice advertised for two positions. The first was for an acoustic consultant, and the second was for a laboratory technician. I applied for the first job, but my application was deemed to be for the second. I was not successful in getting this job and took work at Seimens. I was disappointed, and my father persuaded me to write to Carr and Wilkinson and assure them of my continuing interest. This I reluctantly did. Three months later they contacted me and told me that the job was now available for me if I still wanted it. Believing that I had been successful in obtaining the acoustical consultant's position, I quit my job at Seimens and presented for work at C&W as soon as I could. The premises were just over the road from Swinburne, and I continued there as a part time student for all my time at C&W. At first, I was put to work with electronics. A noise generator had been designed for providing “background sound”, a technique that was new then, to raise the background noise level to improve privacy and to minimize distraction. This saved many of the newly fashionable “open plan” offices from failure. The noise generators were made in very small numbers. I was in charge of manufacturing as well as some further electronic product development.

The practice had a laboratory for acoustic measurements, and I soon became responsible for running this, managing many testing and development projects. I expanded the laboratory facility, particularly the provision for a quiet air supply for testing air conditioning fittings. I set up a variable speed drive for the fan and facilities for air flow measurement. In this role, I invented my dual reservoir manometer, and instrument that combined a manometer and a simple analogue computer performaing a subtraction. This did not have a big impact at the time, but the work was transferred directly into an electrical analogue in a special shunt for the Nilsen Meter in 2002.

Lessons learned.
During this five year period, I learned a lot about acoustics from implications for airconditioning design and speech privacy matters to auditorium design. I learned about sheet metal products development work. I learned about electronic product design and small run manufacture.

I left to pursue my studies for a full time final year.

Siemens Industries , Richmond
1968

In 1968, Siemens had manufacturing facilities in Church Street Richmond. One factory was devoted to the manufacture of frequency division multiplexing equipment for the telephone industry. I worked there for only a few months in the Testing Department.

I was repairing circuit boards that carried double balanced modulators, all made with discrete transistors. Many of the modulators (maybe all?) were single sideband, and elaborate filters with pot core inductors were used to select the required sideband. Colleagues of mine adjusted the pot core inductors on special test sets. Unfortunately, the filter design was obscured, and the set up consisted of instructions such as “Adjust pot core three until the meter points to 7”. When one of the filters did not pass the test, it was very hard to imagine what the problem could be. There was no communication between the design team and us factory workers.
Not a place to learn much.

Lessons learned
Company structure can impose communication barriers (e.g. between a design engineer and a fault finder)

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